The present invention relates to a buffer capacity change monitoring method and a buffer capacity change monitoring apparatus, and in particular, relates to a buffer capacity change monitoring method and apparatus configured so that the extent of the buffer capacity is expanded when the size of an unused region is reduced to a predetermined threshold value.
Moreover, the term "buffer" used in this specification, refers to a memory of a file or some other resource provided with a function for holding data and which has the extent of its capacity within a predetermined range.
The present invention monitors the extent of the buffer capacity and displays a message to that effect on the screen, thereby responding to the need of the system operator or user to know when the extent of the capacity has been expanded.
In the past, a fixed numerical value has been used as a reference value in monitoring expansion of the extent of the buffer capacity. A numerical value such as 70% mentioned below, was defined by the user and used with this fixed reference value. A change in the ratio of buffer usage with time is displayed on a screen. Moreover, in this case, the displayed reference value was the buffer usage ratio at the time when the initial expansion of the buffer extent took place.
FIG. 1 shows the conventional situation prior to the expansion of the extent of a buffer capacity, and FIG. 2 shows the situation after expansion of the extent of the capacity of that buffer. FIG. 1 and FIG. 2, respectively, show the extent of the buffer capacity prior to expansion 100 and after expansion 140. Moreover, formats such as 100 used in this specification express absolute values.
The data which are set beforehand in the status prior to expansion include the following:
The expansion threshold value "b" which indicates the size of the unused region when the expansion takes place; PA1 The reference value "s" which indicates the proportion of the size of the region used to the extent of the buffer capacity, at the time when the expansion takes place; and PA1 The amount by which the region is to be expanded when expansion takes place. PA1 The initial value for the extent of buffer capacity is 800 KB: PA1 The expansion threshold quantity is 100 KB: PA1 The size of one expansion is 200 KB: PA1 The reference value is EQU (800-100)/800 * 100=87.5% PA1 s1 reference value PA1 c' initial value of extent of buffer capacity PA1 b expansion threshold value PA1 c extent of buffer capacity PA1 s1 reference value PA1 b expansion threshold value PA1 c extent of buffer capacity
Moreover, how many times expansion of the extent of the buffer is to be allowed is determined beforehand for each file and memory, and an expanded portion of a buffer is returned when a usable region is freed in a buffer which has been expanded.
FIG. 1 and FIG. 2 show an example where the expansion threshold value "b" and the expansion size are respectively set as the values of 30 and 40, and where the reference value "s" is calculated as 70% from the initial value of 100 for the expansion threshold value 30 and the extent of the capacity.
In addition, the buffer usage ratio and other information at each reference line 21 for the reference value of 70% are displayed on the monitor screen. When the usable region increases and the buffer usage ratio has reached the reference line 21 of 70%. That is to say, when the size of the unused region has reduced to the expansion threshold value "b" of 30, the extent of the capacity is expanded and there is an alarm notifying that expansion is taking place.
The size of the extent of the buffer capacity increases from the level 100, until it reaches 140, and at the next line 22 where expansion takes place, the expansion threshold value of 140 is reduced by 30 to become 110.
However, the reference value stays at the numerical value of 70% and the number 98 corresponding to 70% is displayed on the reference line 21' of the monitor used by the system operator or user.
When there is an increase in the usable region in the buffer, an alarm is given when there is usage of the portion 98, beneath the line 22 where the second expansion will take place.
After this, when the size of the buffer usage region approaches the portion 110 corresponding to the expansion line 22, expansion takes place so that the extent of the buffer capacity is changed from 140 to 180 but there is no notification to the effect that this expansion has taken place.
In a conventional buffer monitoring apparatus, the reference value set beforehand remains displayed as a percentage, in that there is always a linear display in the direction of the x-axis of the monitor. When there is expansion of the extent of the buffer capacity, the portion of intersection of this display line and the buffer usage ratio are correctly displayed when the first expansion takes place, with erroneous display being performed for when later expansions take place. This creates the problem that the system operator or user cannot correctly recognize expansion of the extent of the buffer capacity. The following is a description in terms of a time series, of conventional buffer monitoring.
FIG. 3 is a view showing conventional buffer monitoring in terms of a time series. The following conditions are used as the basis for a description of a specific example of a series of displays corresponding to the transition of statuses at the various times indicated in FIG. 3. In the figure, the shaded portion indicates the amount of the buffer capacity used.
At the time t in FIG. 3, the amount used out of the buffer extent of 800 KB is 400 KB. This is shown as the line 1 in the graph in FIG. 4. Next, at the time 2t in FIG. 3, the amount used becomes 750 KB and expansion of the buffer takes place so that the buffer status changes from that shown in FIG. 3 to that shown in FIG. 4. The graph of FIG. 4 then has 1 plotted as EQU 400/800=50%
which is the information at time it, and 2 plotted as EQU 750/800=93.7%
which is the information at time 2t. At time 2t, the reference value of 87.5% is exceeded and so the buffer is expanded to 1000 KB. 3 is then plotted as EQU 750/1000=75%
for time 3t. Buffer capacity expansion thus takes place when the usage ratio has risen.
When there is transformation from the status at time 3t to the status at time 4t, the usage ratio is the same and so there is no change to the plotted height, and only the portion for the time is plotted (3-4). The next occasion when the extent of the buffer capacity will be expanded will be 5, and will be as follows. EQU (1000-100)/1000 * 100=90%
When there is transformation from the status at time 4t to the status at time 5t, the usage ratio has increased from 750 KB to 880 KB and so EQU 880/1000 * 100=88.8%
is plotted. The extent of the buffer capacity is thus expanded in this manner until a predetermined critical quantity is reached, for each time the usage ratio is increased so that it exceeds the reference value.
However, there are the following problems involved with a display method having a fixed reference value as in the case described above.
First of all, the plot was above the reference value at the time 2t so that the status when the extent of the buffer capacity was expanded could be described. However, the time required to change between the status at time 2t and at time 3t of FIG. 3 is much shorter than the sampling interval t, and there are many instances where is could be either of the situation of the two graphs shown in FIG. 5. This is to say that the system operator cannot know by reading the graph, whether or not expansion actually occurred at time 2t, creating the problem that the expansion may pass unnoticed.
In addition, when there is an increase in the used capacity and 5 is plotted, this can be read as indicating that expansion has actually taken place when the second expansion has not taken place. Accordingly, the person who was operating the system when the initial expansion took place may be slow to detect whatever trouble there is, and an operator who manages a system until the critical point for expansion takes place (while allowing for a certain degree of expansion) may come to the conclusion that there is some trouble even though there may still be a surplus capacity.
The following three methods have been disclosed as a solution to these problems but each of them involves its own problems.
The first method is a method which plots buffer management events on the horizontal axis of a graph. (These events are each data storage to the buffer and each are expansion or reduction of the extent of buffer capacity.) However, with this method, the graph and the status of the buffer are always in perfect agreement but each item is not displayed on the horizontal axis and so it is not possible to make a correspondence with other phenomena, and it is not possible to investigate the cause of changes in the extent of the buffer capacity. In addition, there is also a problem in that it is not possible to make a correspondence between the situation for the load on the system and the actual capacity of the buffer.
The second method is a method which stores the status shown in FIG. 3 in terms of time on a horizontal axis. (In this method, there is sampling of peak values and these peak values are written as current values at the time when the extent of the buffer has been reduced.) Since only changes in the extent of the buffer capacity are displayed, it is not possible to determine the current situation for buffer use. Therefore, this method cannot be said to monitor the situation for buffer use.
The third method is a method which displays an absolute value instead of a usage ratio on the vertical axis of a graph. However, with this method, there is no set scale for the vertical axis. If expansion is repeatedly taking place, it no longer becomes possible to display data which exceeds the scale of the vertical axis (and the graph reaches the top of the screen). Furthermore, even if the scale of the vertical axis can be freely changed (where for example, the current size of the extent of the buffer is scaled so that the maximum value is a scale within the screen), scrolling of the graph causes the scale of the vertical axis to change. The graph becomes extremely difficult to read, and increasing the complexity of control. In addition, if there is a logarithmic graph, the frequency at which the scale changes becomes lower but it is difficult to read changes up and down since the amount used does not change logarithmically.
As can be seen, it is therefore best if the situation for the usage of the buffer is displayed in terms of the usage ratio. In each of the conventional methods, it is not possible to have correct and effective system management when there are changes to the extent of the buffer capacity.